Flu in pregnancy and bipolar disorder

A study funded by the National Institute of Mental Health (NIMH) has found that the risk of bipolar disorder may be quadrupled among children whose mothers contracted influenza in pregnancy.

The findings were published online May 8, 2013, by JAMA Psychiatry.

The researchers conducted a study of a population-based birth cohort from the Child Health and Development Study (CHDS). From January 1, 1959, through December 31, 1966, the CHDS recruited nearly all pregnant women receiving obstetric care from the Kaiser Permanente Medical Care Plan, Northern California Region (KPNC). Data on treated maternal influenza from the CHDS were used. Potential cases with BD from the cohort were identified by database linkages of identifiers among the CHDS, Kaiser Permanente database, and a large county health care database; by a mailed questionnaire to the CHDS cohort with subsequent interviews; and from an earlier psychiatric follow-up study on this birth cohort.

The researchers found a significant, nearly 4-fold increase in the risk of BD (odds ratio, 3.82 [95% CI, 1.58-9.24; P =.003]) after exposure to maternal influenza at any time during pregnancy. The findings were not confounded by maternal age, race, educational level, gestational age at birth, and maternal psychiatric disorders.

“Prospective mothers should take common sense preventive measures, such as getting flu shots prior to and in the early stages of pregnancy and avoiding contact with people who are symptomatic,” said Alan Brown, MD, MPH, of Columbia University and New York State Psychiatric Institute, in an NIMH press release. “In spite of public health recommendations, only a relatively small fraction of such women get immunized. The weight of evidence now suggests that benefits of the vaccine likely outweigh any possible risk to the mother or newborn.”